Artificial filament manufacture and the like



Nov 10, 1936. H. DREYFUS 2,060,048

ARTIFICIAL FILAMENT MANUFACTURE AND THE LIKE Filed Aug. 22, 1932 FIGiJ- "m hdm Patented Nov. 10, 1936 UNITED STATES PATENT OFFICE ARTIFICIAL FILAMENT 'MANUFACTURE AND THE LIKE Henry Dreyfus, London, England 8 Claims.

This invention relates to the production of artificial filaments, threads, ribbons, films and the like from solutions of cellulose acetate or other suitable spinning solutions, for example solutions of other esters of cellulose or of cellulose ethers or ether-esters.

In U. S. Patent No. 1,934,618 and application S. No. 485,410 filed September 30, 1930, processes and apparatus are described whereby in the dry spinning of solutions of cellulose acetate or other cellulose derivatives in which the solution is extruded into a counter-current of evaporative medium, additional evaporative medium is introduced into the said current in the vicinity of the jet. In U. S. Patent No. 1,934,618 arrangements are described whereby additional air may be introduced at oneside of the filaments and blown across the path of the filaments or may be introduced from outside a ring of filaments and blown radially inwards, and in U. S. application S. No. 485,410. arrangements are described whereby additional .air may be introduced from inside the ring of filaments and blown outwards. The introduction of additional air or other evaporative medium in this manner considerably improves the cross-section of the filaments.

I have now found that the advantages inherent in the processes described in U. S. Patent No. 1,934,618 and application S. No. 485,410 may further be achieved by a similar introduction of additional air or other evaporative medium in the vicinity of the jet while spinning the filaments or other products into an evaporative medium moving in the same direction as the spun products.

For introducing such additional air or other evaporative medium, devices similar to those adopted in U. S. Patent No. 1,934,618 and application S. No. 485,410 may be used. Instead, however, of introducing evaporative medium at the bottom of the cell in spinning downwardly and withdrawing such evaporative medium towards the top of the cell, such current of evaporative medium is introduced towards the top and withdrawn below the nozzle in downward spinning or vice versa in upward spinning. The additional evaporative medium may be introduced at one side of the filaments and blown or sucked across the path of the filaments or may be introduced symmetrically around the filaments so as to impinge radially thereon.

As a further modification, instead of introducing additional evaporative medium into a current of evaporative medium moving in the same direction as the filaments, the invention further includes introducing the whole of the evaporative medium in the vicinity of the jets or at some distance from the jet on the extrusion side thereof, and causing a part of such medium to proceed in the same direction .as the filaments and the remainder to proceed in the opposite direction, i. e. in counter-current to the direction of the filaments. This modification is especially of value where the injector for the air or evaporative medium is below the level of the jet face in the case of downward spinning or above the level of the jet face in the case of upward spinning.

The distance from the jet .at which the medium is introduced may vary, for example, from half-an-inch to 3-6 inch-es or more, i. e. considerably nearer one end of the cell than the other or it may even be half the total run of the filaments in the spinning cell or chamber.

The relative proportions of additional evaporative medium and co-current of evaporative medium, or of the two currents of evaporative medium in the case of the modification, may be adjusted to any desired value. Thus the additional evaporative medium may be comparatively small in relation to the total quantity of evaporative medium employed or may comprise practically all the air proceeding through the cell, the co-current being constituted by a very slow current of air. Similarly, in the case of introducing the whole of the medium into the jet neighbourhood or at a point intermediate along the run of the filaments and causing such medium to divide into two currents, the volume proportions of the two currents may be varied considerably. Preferably, the volume of the current proceeding counter to the filaments is increased with increasing distance between the point of introduction of the medium and the jet.

The filaments may be drawn out by applying a tension operative directly from the spinning nozzle or by applying tension between any two points of their path. They may even be stretched outside the spinning cell. For facilitating a stretch outside the spinning cell, or in the later stages of drying inside the cell, the filaments may be caused to retain sufficient solvent or softening agent in any desired manner, for instance by incorporating in the spinning solution relatively high boiling solvents. Alternatively, the filaments proceeding from the cell or casing may be treated with suitable solvents or gelling agents for the cellulose derivative and the stretch suitably applied. In this connection reference is made broadly to U. S. application S. No. 378,684 filed July 16, 1929, which describes the application of such additional stretch to the filaments continuously with spinning. Additional stretch may be applied to the filaments in the actual spinning cell, and in order to ensure that the whole of such additional stretch does not operate from the nozzle itself, as in the normal dry spinning processes, means may be adopted, such as those described in U. S. application S. Nos. 463,932 filed June 26, 1930, and 476,334 filed August 19, 1930, to prevent the whole of the stretch running back to the spinning nozzle itself.

Draw down from the spinning nozzle may be improved by pre-heating the spinning solution, for instance by the means described in U. S. application S. No. 375,151 filed July 1, 1929, or such heating may be applied for other purposes.

The invention will now be described in greater detail with reference to the accompanying drawing, but it is to be understood that this description is given by way of example only and is in no way limitative.

Figure l is a sectional elevation of apparatus according to the invention;

Figure 2 shows a modification of the top of the cell shown in Figure 1;

Figure 3 shows a further form of apparatus;

Figure 4 is a view in section along the line 4-4 of Figure 3;

Figure 5 shows a further modification of the apparatus; and

Figure 6 shows a modification of the apparatus shown in Figure 1.

Referring to Figure 1 a spinning cell In is provided with a supply pipe II for a spinning solution of cellulose acetate or other organic derivative of cellulose, which solution passes through a filter candle 2 to a spinning jet |3, the filaments l4 extruded from the jet proceeding down the length of the cell, round a guide l5 and out at the opening IS. The evaporative medium enters the cell through a perforated ring I! fed by a pipe l8, such medium being provided from a pressure header H! by way of suitable valve 28 or by any other convenient means. The ring I! may be somewhat below the jet, as shown, or at the jet level or even somewhat higher. Evaporative medium introduced through the ring I! passes down the cell and is drawn off by means of a draw-01f pipe 2| leading into a header 22, valve means 23 being provided in order that the rate of draw-off may be adjusted at this point. A flow gauge 24 may be connected to the pipe 2| if desired.

A proportion of the evaporative medium entering by the ring H, however, may pass upwardly and be drawn off through the pipe 25 into a header 26, similar control apparatus 26 and gauge 24 being provided as with the draw-off pipe 2|. The ratio of the quantities of evaporative medium passing upwardly to the draw-off pipe 25 and downwardly to the pipe 2| may be adjusted by means of the valves 23 and gauges 24 in connection with such draw-off pipes. The number of holes on the upper and lower sides of the ring I! may vary in accordance with the quantity of air required to pass to the pipes 25 and 2| respectively.

After extrusion, the filaments leaving the opening l6 may pass over a Wick 29 fed with suit able solvents or gelling agents for the cellulose acetate or other cellulose derivative of which the filaments consist. The filaments softened by the solvent then proceed round two rollers 3|, 32, the roller 3| rotating at a lower speed than the roller 32 so that between the rollers the filaments are stretched. The speed of the roller 3| may be such that the filaments are stretchd within the cell. On leaving the roller 32 the filaments proceed to the balloon guide 33 of a cap spinning device 34 by means of which they are twisted, and wound on a bobbin 35.

In Figure 2 means are provided on an apparatus of the kind shown in Figure 1 for heating the spinning solution prior to extrusion in a manner described in U. S. application S. No. 375,151. The spinning solution is fed from a header 45 by means of a pump 4! through a coiled pipe 42 contained in a bath &3, the bath 43 being heated by means of heating coils i l. The pipe 42 proceeds to a filter candle 45 and thence by way of pipe 46 to the spinning jet I3, both filter 45 and pipe 46 being carefully insulated by means of lagging ll from the influences of the evaporative medium contained in the cell. If desired, the filter candle 45 may be replaced by a candle 59 shown in dotted lines within the heated bath 43, the spinning solution then being heated as it passes through the filter.

In Figure 3 means are shown for introducing additional evaporative medium into a co-current of evaporative medium passing in the same direction as the filaments. The main current of evaporative medium enters by the pipe 48 and leaves by the draw-ofi pipe 2|, additional evaporative medium being introduced at the side of the filaments through a pipe 50 which may be provided with a specially formed air nozzle 5| as more clearly shown in Figure 4. The pipe 50 is pivoted at 52 in order that it may be swung out of the way to allow the jet E3 to be reached through the door 53 at the top of the cell. In this figure a perforated diaphragm 55 is provided across the cell just below the level of the jet |3 which constrains the evaporative medium entering through the pipe 38 to pass in the immediate vicinity of the filaments issuing from the jet I3. In addition, further draw-01f means are provided at 53 just below the level of air nozzle 5| so that some of the evaporative medium may be drawn off at this point.

Means are shown in Figure 3 for stretching the filaments inside the cell, rods 69 being provided in and out of which the filaments pass, so that stretch which is applied by the roller 3! outside the cell is prevented from running back to the spinning jet l3 itself.

A somewhat more simple form of apparatus is shown in Figure 5, wherein, as in Figure 3, the main current of evaporative medium enters the cell by the inlet 68 and leaves the cell by the draw-off pipe 2 5. Additional evaporative medium is introduced into this co-current by means of a perforated annular tube 62, symmetrically disposed round the filaments, and fed through a pipe 6i provided with a valve 28. The evaporative medium leaving the ring 62 impinges upon the filaments in the neighbourhood of the jet I3 and joins the main current of evaporative medium, passing down the cell and leaving with the main current by the draw-01f 2|. The filaments l3 after leaving the cell ID by the opening |6 may be passed over a wick 23 and stretched by means similar to those in Figure 1.

Figure 6 shows a modification of the apparatus illustrated in Figure 1, wherein, however, the air is introduced by a perforated ring 63 fed by a pipe 6 3, the tube 63 being disposed about mid-way between the spinning jet l3 and the guide |5 round which the filaments pass to leave the cell I through the opening I 6. As in Figure 1 the evaporative medium entering by the annular tube 63 leaves the cell by way of draW-ofi tubes 2|, 25 disposed at the bottom and top of the cell respectively. In this case, however, the proportion of evaporative medium passing upwardly to the draw-off 25 should be greater than in Figure 1 in View of the fact that a greater length of filaments I4 lies above the ring 63. The adjustment of the proportion of evaporative medium passing upwards may be effected as in Figure 1 by means of a control apparatus in connection with the draw-off tubes 2|, 25.

What I claim and desire to secure by Letters Patent is:

1. Process for the production of artificial filaments, threads, yarns, straws, ribbons and the like by the dry or evaporative method, which comprises setting up a current of evaporative medium, extruding a dry spinning solution containing a volatile solvent, causing the extruded products to pass through said current in the direction of flow thereof and introducing into said current at a point along the path of the extruded products an additional flow of evaporative medium, said additional fiow of evaporative medium flowing in the direction of the extruded products.

2. Process for the production of artificial filaments, threads, yarns, straws, ribbons and the like by the dry or evaporative method, which comprises setting up a current of evaporative medium, extruding a dry spinning solution containing a volatile solvent, causing the extruded products to pass through said current in the direction of flow thereof, introducing into said current at a point along and to one side of the path of the extruded products an additional flow of evaporative medium, and withdrawing a part of the evaporative medium at a point opposite the point of introduction of the additional evaporative medi- 3. Process for the production of artificial filaments, threads, yarns, straws, ribbons and the like by the dry or evaporative method, which comprises setting up a current of evaporative medium, extruding a dry spinning solution containing a volatile solvent, causing the extruded products to enter and pass through said current in the direction of flow thereof and substantially at the point of entry of said products introducing an additional flow of evaporative medium along the path of said products in the opposite direction thereto.

4. Process for the production of artificial filaments, threads, yarns, straws, ribbons and the like by the dry or evaporative method, which comprises setting up a current of evaporative medium, extruding a dry spinning solution containing a volatile solvent, causing the extruded products to enter said current at a point near the point of extrusion and to pass through said current in the direction of flow thereof, introducing an additional flow of evaporative medium at substantially said point of entry and causing said additional flow to fiow in a direction opposite to the direction of extrusion.

5. Process for the production of artificial filaments, threads, yarns, straws, ribbons and the like from solution of cellulose acetate by the dry or evaporative method, which comprises extruding a solution of cellulose acetate in a volatile solvent, causing the extruded products to pass through said current in the direction of flow thereof and introducing into said current at a point along the path of the extruded products an additional fiow of evaporative medium, said additional flow of evaporative medium flowing in the direction of the extruded products.

6. Apparatus for the production of artificial filaments, threads, yarns, straws, ribbons and the like by the dry or evaporative method, comprising a spinning cell, means for causing a current of evaporative medium to fiow along said cell, a spinning jet disposed in said cell for the extrusion of a spinning solution through said current, said jet facing in the direction of flow of said current, and a ring nozzle disposed within said cell and encircling the path of the extruded products in the neighborhood of said jet for introducing additional evaporative medium into said current.

7. Apparatus for the production of artificial filaments, threads, yarns, straws, ribbons and the like by the dry or evaporative method, comprising a spinning cell, means for causing a current of evaporative medium to flow along said cell, a spinning jet disposed in said cell for the extrusion of aspinning solution through said current, said jet facing in the direction of fiow of said current, a nozzle disposed within said cell on one side of the path of the extruded products for introducing additional evaporative medium into said current, and a draw-oil tube disposed within said cell on the other side of said path and adapted for the withdrawal of evaporative medium from said current.

8. Apparatus for the production of artificial filaments, threads, yarns, straws, ribbons and the like by the dry or evaporative method, comprising a spinning cell, means for causing a current of evaporative medium to flow along said cell, a spinning jet disposed in said cell but out of said current for the extrusion of a spinning solution through said current, said jet facing in the direction of flow of said current, and means for directing an additional fiow of evaporative medium along the path of the extruded products and towards said jet.

HENRY DREYFUS. 

